Multiple-stage slurry processing for black oil conversion

ABSTRACT

A catalytic slurry process for effecting the conversion of a hydrocarbonaceous charge stock containing asphaltenes, metallic contaminants and excessive quantities of sulfurous compounds. The slurry constitutes the charge stock, hydrogen and from about 1.0 percent to about 25.0 percent by weight of finely divided catalyst particles. The charge stock is converted by processing the slurry in at least two individual reaction zones having separation facilities therebetween. That portion of the first reaction zone product effluent containing the catalyst particles and unconverted nondistillables is processed in a succeeding reaction zone. At least the major portion of the product effluent from the succeeding reaction zone is recycled to combine with the fesh feed charge stock. Preferred catalysts are the unsupported sulfides of the metals from Groups V-B, VI-B and VIII.

United States Patent 1,890,434 12/1932 Krauchetal.

Inventors Appl. No.

Filed Patented Assignee MULTIPLE-STAGE SLURRY PROCESSING FOR BLACK OIL CONVERSION 6 Claims, 1 Drawing Fig.

US. Cl......

208/108, 208/215, 208/251 1m. c1 B01] 11/74, c10 13/015,010; 23/16 Field of Search 208/59, 208; 252/414, 439, 432, 437, 455 R References Cited UNITED STATES PATENTS Primary Examiner-Delbert E. Gantz Assistant Examiner-G. E. Schmitkons Attorneys-James R. Hoatson, Jr. and Robert W. Erickson ABSTRACT: A catalytic slurry process for effecting the conversion of a hydrocarbonaceous charge stock containing asphaltenes, metallic contaminants and excessive quantities of sulfurous compounds. The slurry constitutes the charge stock, hydrogen and from about 1.0 percent to about 25.0 percent by weight of finely divided catalyst particles. The charge stock is converted by processing the slurry in at least two individual reaction zones having separation facilities therebetween. That portion of the first reaction zone product efiluent containing the catalyst particles and unconverted nondistillables is processed in a succeeding reaction zone. At least the major portion of the product effluent from the succeeding reaction zone is recycled to combine with the fesh feed charge stock. Preferred catalysts are the unsupported sulfides of the metals from Groups VB, Vl-B and VIII;

Make-up Hydrogen 1| 4 0 1 [Heater Ghare g 1 I] Hat Separator 00/0 Separa tar p t x Q m x b a E w /7 o L};

5 Catalyst Recovery l MULTIPLE-STAGE SLURRY PROCESSING FOR BLACK OIL CONVERSION The process described herein is applicable to the conversion of petroleum crude oil residuals having a high metals content and comprising a hdydrocarbon-insoluble asphaltene fraction. More specifically, our invention is directed toward a method for effecting a catalytic slurry process, in the presence of hydrogen, to convert atmospheric tower bottoms, vacuum column bottoms, crude oil residuals, topped and/or reduced crude oils, coal oil extracts, crude oils extracted from tar sands, etc., all of which are commonly referred to in the art as "black oils."

Petroleum crude oils, and particularly the heavy residuals derived therefrom, contain sulfurous compounds in exceedingly large quantities, nitrogenous compounds, high molecular weight organometallic complexes principally comprising nickel and vanadium as the metallic component, and hydrocarbon-insoluble resinous and asphaltenic material. The latter is generally found to be complexed with sulfur, oxygen and nitrogen, and to a certain extend, with the metallic contaminants, and is insoluble in light hydrocarbons such as propane, pentane and/or heptane. A black oil is generally characterized in petroleum technology as a heavy hydrocarbonaceous material of which more than about 10.0 percent (by volume) boils have a temperature of about l,050 F. (referred to as nondistillable) and which further has a gravity generally less than about 200' AH. Sulfur concentrations are exceedingly high, most often in the range of about 2.0 percent to about 6.0 percent by weight. Conradson carbon residual factors generally exceed 1.0 percent by weight, and the concentration of metallic contaminants can range from as low as 20 p.p.m. to as high as about 2,000 p.p.m. by weight, computed as the elemental metals.

The process encompassed by the present invention is particularly directed toward the conversion of those black oils contaminated by large quantities of insoluble asphaltenes and having a high metals content-i.e. containing more than about l50 p.p.m. by weight. Specific examples of the charge stocks to which our invention is adaptable, include a vacuum tower bottoms product having a gravity of about 7. 1 API and containing about 4.! percent by weight of sulfur and 23.7 percent by weight of heptane-insoluble material; a topped Middle- East crude oil having a gravity of ll.0 API and containing about 10.1 percent by weight of asphaltenes and 5.2 percent by weight of sulfur; a crude oil having a gravity of 8.l AP], and containing l6.8 percent of heptane-insoluble material and 1,300 p.p.m. of metals; a reduced crude oil having a gravity of 9.8 APl, containing 5.2 percent by weight of heptane-insoluble material, and of which only about 32.0 percent (by volume) boils below a temperature of about l,050 F.; and, a reduced crude having a gravity of 7.7 API, and containing 12.8 percent by weight of heptane'insoluble material and about 190 p.p.m. by weight of metals.

The utilization of our invention affords the conversion of such material into distillable hydrocarbons, or waxy material free from contaminants, heretofore having been considered virtually impossible to achieve on a continuous basis with an acceptable catalyst life. Our invention further reduced the quantity of material withdrawn from the process as a drag stream, makes the separation of catalyst less difiicult and effects continuous regeneration of the catalyst particles. The principal difficulty, encountered in a fixed-bed catalytic system, resides in the lack of sufiicient catalyst stability in the presence of relatively large quantities of metals i.e. from about 150 p.p.m. to as high as 2,000 p.p.m., computed as the elements and additionally from the presence of large quantities of asphaltenic material and other nondistillable hydrocarbons. The asphaltenic and resinous material consists primarily of high molecular weight coke precursors, insoluble in light normally liquid hydrocarbons such as propane, pentane and/or heptane. Asphaltenes and resins are generally found to be dispersed within the black oil, and, when subjected to elevated temperature have the tendency to flocculate and polymerize whereby the conversion thereof to more valuable oil-soluble products becomes extremely difficult.

Gender compels recognition of the many slurry-type processes which have heretofore been proposed. Regardless of the various operating and processing techniques, a major difiiculty residues in the quantity of carbon which coats the catalytic particles. Analyses have indicated that the spent" catalyst particles will contain from about 15.0 percent to as high as 25.0 percent by weight of carbon. This excessive carbon lay-down inherently necessitates the removal, on a continuous basis, of large quantities of catalyst to recovery facilities. This in turn requires the use of intricate equipment at prohibitively high cost, and makes the process economically unattractive. An obvious alternative is to utilize the hydrocarbonaceous black oil as the charge to a coking unit for the production of coke and distillable hydrocarbons. In view of the steadily increasing demand for distillable hydrocarbons, particularly motor fuels, jet fuels and naphtha stocks for conversion into liquefied petroleum gas, coking is not a suitable alternative due to its relatively low yield of distillable hydrocarbons. Through the utilization of our invention, there is provided a more economical and significantly less difficult process for the conversion of hydrocarbonaceous black oils to distillable hydrocarbons.

OBJECTS AND EMBODIMENTS A principal object of our invention is to convert nondistillable hdyrocarbonaceous material into lower boiling distillable hydrocarbons, or waxy material free from contaminants. A corollary objective is to provide a catalytic slurry process for the hydrogenative conversion of an asphaltene-containing, black oil charge stock.

Another object is to convert a black oil charge stock into distillable hydrocarbons, through the use of a multiple-stage system, with minimum yield loss to unconverted asphaltenecontaining residuum.

Therefore, in one embodiment, our invention provides a process for converting an asphaltene-containing hydrocarbonaceous charge stock which comprises the steps of: (a) forming a reactive slurry of said charge stock, hydrogen and a finely divided catalyst of at least one metal component from the metals of Groups V-B, Vl-B or Vlll; (b) reacting said slurry in a first reaction zone, at a temperature above about 300 C. and a pressure greater than about 500 p.s.i.g.; (c) separating the resulting reaction zone effluent, in a first separation zone, at substantially the same pressure and a temperature above about 350 C. to provide a first vaporous phase and catalyst-containing first liquid phase; (d) reacting said first liquid phase, in a second reaction zone, at a pressure greater than about 500 p.s.i.g. and a temperature above about 300 C.; and, (e) recycling at least a portion of the resulting second zone effluent to combine with said charge stock.

Other embodiments of our invention are directed toward particular operating techniques and preferred ranges of operating variables and conditions. Thus, the process is further characterized in that the catalyst concentration, within the slurry being introduced into the reaction chamber, is in the range of from about 1.0 percent to about 25.0 percent by weight, based upon fresh feed charge stock, and preferably from about 2.0 percent to about 15.0 percent. Similarly, the first reaction zone effluent may be initially separated by way of propane deasphalting to provide a phase containing catalyst, resins and asphaltenes. This propane-insoluble phase is then further reacted in the second reaction zone.

SUMMARY OF THE lNVENTlON The use of a particular finely divided solid catalyst, in the present slurry process, is not considered to be an essential feature. However, it must be recognized that preferred catalytically active metallic components possess both cracking and hydrogenation activity. ln most applications of our invention, the catalytically active metallic components, or component, will be selected from the metals of Groups VB, Vl-B or VIII of the The Periodic Table. Thus, in accordance with the The Periodic Table of the Elements, E. H. Sargent & Co., I964, the

preferred metallic components are vanadium, chromium, iron, cobalt, nickel, niobium, molybdenum, tantalum and/or tungsten. The noble metals of Group VIII, namely ruthenium, rhodium, palladium, osmium, iridium and platinum are not generally considered for use in a slurry-type process in view of the economic considerations involved with these relatively expensive metals, as well as their sensitivity toward sulfur-containing oils. The foregoing metallic components may be combined with a refractory inorganic oxide carrier material, including alumina, silica, zirconia, magnesia, titania, mixtures of two or more, etc., the final composite being reduced to a finely divided state. In such a composite, the active metallic components may exist in some combined fonn such as the oxide, sulfide, sulfate, carbonate, etc. Recent investigations and developments in catalytic slurry processing of heavy hydrocarbon charge stocks have indicated that the sulfides of the foregoing metals, particularly those of Group V-B, offer more advantageous results. Furthermore, the process appears to be facilitated when the sulfide of the metal is unsupported, as contrasted, to being combined with a refractory inorganic oxide carrier material. For this reason, the preferred unsupported catalyst for use in the process of the present invention, comprises tantalum, niobium or vanadium sulfides, the latter being particularly preferred. In the interest of brevity, the following discussion will be limited to the use of vanadium sulfides in an amount of about 1.0 percent to about 25.0 percent by weight, as the catalyst in the present sluny process.

Regardless of the character of the catalyst, it may be prepared in any suitable, convenient manner, the precise method not being an essential feature of the present invention. For example, vanadium sulfides may be prepared by reducing vanadium pentoxide with sulfuric acid, sulfur dioxide and water to yield a solid hydrate of vanadyl sulfate. The latter is treated with hydrogen sulfide at a temperature of about 300 C. to form vanadium tetrasulfide. Reducing the vanadium tetrasulfide in hydrogen, at a temperature above about 300 0, produces the vanadium sulfide slurried into the system. As hereinbefore set forth, the concentration of vanadium sulfide is preferably within the range of about 2.0 percent 15.0 percent by weight, calculated as the elemental metal. Excessive concentrations do not appear to enhance the results, even with extremely contaminated charge stocks having exceedingly high asphaltene contents.

Briefly, the present invention involves the utilization of a multiple-stage system. The charge stock, catalyst and hydrogen slurry are initially reacted in a first reaction zone, and the product therefrom separated to provide a catalystcontaining liquid phase, or a propane-insoluble phase, and a first principally vaporous phase. The catalyst-containing liquid phase, with or without the addition of hydrogen, and/or hydrogen sulfide, is further reacted in a second reaction zone, the greater portion of the product therefrom being recycled to combine with the charge stock. As hereinafter indicated a portion of the. catalyst-containing second reaction zone effluent is sent to a catalyst separation and recovery system. Generally, this drag system will be in an amount such that about 2.0 percent to 20.0 percent by weight of the catalyst, initially admixed with the charge stock, is removed from the process. Other operating details will be given in the following description of the accompanying drawing.

DESCRIPTION OF DRAWING In the accompanying drawing, illustrating one embodiment of the present invention, a simplified flow diagram is presented. Details such as pumps, instrumentation and controls, heat-exphange and heat-recovery circuits, valving, startup lines, and similar hardware have been omitted; these are considered nonessential to an understanding of the techniques involved. The use of such miscellaneous appurtenances, to modify the illustrated process flow, are well within the purview of those skilled in the art. Similarly, it is understood that the charge stock. stream compositions, operation conditions,

catalysts, design of fractionators, separators and the like are exemplary only, and may be varied widely without departure from the spirit of our invention, the scope of which is defined by the appended claims.

With reference now to the drawing, the charge stock, for example a reduced crude, is introduced into the process by way of line 1, and is admixed therein with a hydrogen-rich recycled vaporous phase in line 3 and catalyst-containing liquid phase from line 2. Following heat-exchange with hot effluent streams, which technique is not illustrated, the mixture continues through line 1 into heater 5. With respect to the total charge mixture, the hydrogen concentration is in the range of about 1,000 to about 50,000 sctZ/bbl. of fresh charge stock, and preferably from about 5,000 to about 20,000 sctZ/bbL, including makeup hydrogen which may be introduced by way of line 4. The concentration of catalyst is in the range of about 1.0 percent to about 25.0 percent by weight, and preferably from 2.0 percent to about 15.0 percent by weight, calculated.

as the elemental metal. Heater 5 increases the temperature of the mixture to a level in the range of about 300 C. to about 500 C., the the heated mixture being introduced into reactor 7 by way of line 6 at a pressure in the range of about 500 to about 4,000 p.s.i.g., and preferably from about L000 to about 3,000 p.s.i.g. Although the heated charge mixture is shown as entering reactor 7 in upflow direction, our invention is not intended to be limited thereto since downward flow is also suitable. Similarly, in order to assure intimate mixing and contacting of the reactants, a variety of mechanical devices such as spray nozzles, bayonets, distributing grids, etc., may be employed within reaction chamber 7. The residence time depends upon a multitude of considerations not the least of which involves temperature, the degree of mixing, catalyst concentration, charge stock characteristics, the degree of conversion and the volumetric ratio of recycled material to fresh feed. In most applications of our invention, the residence time will range form about 30 seconds to about 2 hours.

The effluent from reaction 7 is withdrawn by way of line 8 and introduced thereby into hot separator 9 at a temperature of 700 F. to about 900 F. Hot separator 9 functions at substantially the same pressure as that imposed on reactor 7. As utilized herein, the phrase pressure substantially the same as" is intended to indicate that the pressure of a succeeding downstream vessel is the same as that of the upstream vessel, allowing only for the nonnal pressure drop experienced as a result of fluid flow through the system. Hot separator 9 serves to provide a first principally vaporous phase withdrawn as an overhead product by way of line 10, an containing the lighter components of the cracked product effluent, primarily hydrogen, hydrogen-sulfide, ammonia, normally gaseous hydrocarbons and distillable hydrocarbons boiling below a temperature of about 900 F. A first principally liquid phase is withdrawn from hot separator 9 by way of line 13. Hot separator 9 functions 9 in the manner which provides for the greater proportion of catalyst being removed in this normally liquid phase. The vaporous phase in line 10 is cooled and condensed to a temperature in the range of about 60 F. to about l40 F and passes therethrough into cold separator 11. A hydrogenrich vaporous phase is withdrawn from cold separator 11 by way of line 3, and is recycled therethrough to combine with the charge stock in line 1. The recycled vaporous phase may be treated by any means well known in the art for the purpose of removing hydrogen sulfide and other gaseous components in order to increase the hydrogen concentration prior to being combined with the charge stock in line 1. The normally liquid phase withdrawn from cold separator 11, by way of line 12, constitutes the product of the present process.

The catalyst-containing liquid phase in line 13, with or without added hydrogen and/or hydrogen sulfide, is introduced into a second reaction zone 14, in either upward, or downward flow, wherein additional conversion to lower boiling hydrocarbon products is effected and substantial quantities of carbonaceous material are removed from the finely divided catalyst particles. The product effluent from reactor 14 is withdrawn by way of line 15, a portion thereof being divided through line 16 into catalyst separation zone 17. The remainder of the product effluent is recycled by way of line 2 to combine with the fresh feed charge stock in line 1. The quantity of effluent diverted through line 16 is such that about 2.0 percent to about 20.0 percent by weight of the quantity of catalyst employed is withdrawn from the process. Within catalyst separation zone 17, any suitable means may be utilized to separate solid catalyst particles from liquid phase hydrocarbons, including filtration, settling tanks, a series of centrifuges, etc. The hydrocarbons thus removed from the catalyst particles are recycled by way of line 2 to combine with the fresh feed charge stock in line 1. The catalyst-containing sludge, comprising unreacted asphaltenes, is considered a drag stream and may be treated in any manner which produces a vanadium sulfide for reuse within the process. The sludge being removed by way of line 18, may be burned in air to produce vanadium pentoxide. This is subsequently reduced with sulfur dioxide, sulfuric acid and water to produce vanadyl sulfate. The procedure then follows the previously described scheme for the preparation of fresh vanadium sulfide. The process may also be effected in a manner wherein the first zone effluent is subjected to propane deasphalting. This has the advantage that only catalyst, resins and unconverted asphaltenes and introduced into the second reaction zone.

EXAMPLES The following examples are presented to illustrate further the process encompassed by our invention. It is understood that the invention is not to be considered limited to the charge stock, catalyst, operating conditions and techniques, concentration of reactants, etc.

Our invention is principally founded upon recognition of the fact that (l) reacted, but unconverted asphaltenes have a character different from native asphaltenes contained in a fresh charge stock, and (2) these asphaltenes can be further processed with deactivated catalyst to produce additional normally liquid, lower boiling hydrocarbon products while simultaneously effecting substantial carbon removal from the catalyst particles.

Unsupported vanadium sulfide catalyst is prepared in situ" from a precursor, vanadium tetrasulfide. Generally, the technique involves dispersing finely divided vanadium tetrasulfide into the fresh feed charge stock; upon being subjected to elevated temperature and pressure, in the presence of hydrogen, the tetrasulfide decomposes to form the catalytic vanadium sulfide. Recovered spent" catalyst is generally found to have the following approximate composition: 38.0 percent to about 42.0 percent by weight of vanadium, 29.0 percent to about 34.0 percent by weight of sulfur, 13.0 percent to about 18.0 percent by weight of carbon, or more, and 1.0 percent to about 2.0 percent by weight of hydrogen.

Reprocessing the used catalyst with the total fresh feed charge stock neither appreciably increases the carbon content, nor changes significantly the approximate composition as above set forth. When either a nonaromatic feed stock, such as a heavy mineral oil,, or a low-boiling aromatic hydrocarbon, such as Tetralin, is used to reprocess the used catalyst, the composition is not significantly altered. We have found that the catalyst, when reprocessed with a high-boiling, highly aromatic stock, such as a clarified cycle oil from a catalytic cracking process, loses a significant quantity of carbon and can be considered regenerated sufficiently to be reused in processing fresh charge stock. Product bottoms, resulting from the initial processing of the charge stock, is highly aromatic, the asphaltenes have been upgraded to a certain extent and can be used to reprocess the catalyst to a lower carbon content, while simultaneously producing additional lower boiling hydrocarbon products. This phenomenon is demonstrated in the following specific illustrations.

EXAMPLE 1 The charge stock was a topped" crude oil having a gravity of 8.9 AP], being about 55.5 percent distillable (at a temperature of l,050 F.), and containing 10.53 percent by weight of heptane-insoluble asphaltenes, 2.8 percent by weight of sulfur, 5,100 p.p.m. by weight of nitrogen, 525 p.p.m. of vanadium and about 46 p.p.m. by weight of nickel. A vanadium sulfide, finely divided composite was commingled with the charge stock in an amount of 6.8 percent by weight. Operating conditions were: a charge stock rate of 200 g./hr., a hydrogen recycle rate of 18.9 scf./hr. (about 5,000 scf./bbl.,) a pressure of 3,000 p.s.i.g. and a temperature gradient of 380-430 C. 7 l 6-06 F.

A series of six runs were performed, each succeeding run utilizing the catalyst separated from the product effluent from the previous run. The results from the first run, with respect to the normally liquid product effluent, indicated a gravity of about l8.4 APl, about 79.5 percent distillable hydrocarbons, 0.40 percent by weight of unconverted asphaltenes, about 0.8 percent by weight of sulfur, 2,250 p.p.m. of nitrogen and 35 p.p.m. of total metals. Following the sixth run, it was noted that the catalyst had become deactivated. This was evidenced by a light product gravity of about l5.3 APl about 2.80 percent by weight of heptane-soluble asphaltenes, 1.65 percent sulfur, about 3,400 p.p.m. by weight of nitrogen and 60 p.p.m. of total metals.

The product bottoms from the first, second and fifth runs, approximately 970 F. plus material, were blended to form a charge stock having a gravity of 8.0 API and containing 4.0 percent heptane-insoluble asphaltenes; about 20.0 percent by volume was distillable at a temperature of l,l00 F. This charge was reprocessed, in an amount of about 197 g., with about 46 g. of the used catalyst, in an 1,800 cc. rocker-type autoclave. Conditions included a pressure of about 300 atmospheres and a temperature of 380 C. The autoclave was initially pressured to atmospheres with hydrogen containing about 20.0 percent hydrogen sulfide. Whereas the used catalyst had indicated a carbon content of 17.02 percent, anaylsis of the autoclave catalyst indicated 12.82 percent by weight of carbon. The catalyst was separated from the autoclave effluent, and the liquid product analyzed. The gravity was 19.0" AP! and 80.0 percent by volume was distillable at a temperature of 1,l03 F.; the product had an initial boiling point of 364 F. and a 50.0 percent volumetric distillation temperature of 978 F., and contained only 0.49 percent by weight of heptane-insoluble asphaltenes.

EXAMPLE II In a second operation, 151 g. of a 1,l00 F. plus bottoms blend from runs one, three, four and five were processed in the autoclave with 84 g. of the spent" vanadium sulfide catalyst. The autoclave was maintained at a pressure of 280 atmospheres and 380 C. in an atmosphere of hydrogen containing about 20.0 percent hydrogen sulfide. The autoclave catalyst indicated a carbon content of 13.4 percent by weight, and the liquid product, 70.0 percent by volume of which boiled below about 1,] 19 F., had a gravity of APl.

EXAMPLE Ill Forty grams of used catalyst, having an analyzed carbon content of 15.87 percent by weight, were reprocessed in the 1,800 cc. autoclave at a pressure of 205 atmospheres and a temperature of 425 F., for a period of about 3 hours. The charge stock was a clarified slurry oil (200 grams) obtained from a catalytic cracking process. Pertinent properties of this charge stock and the liquid product from the autoclave are tabulated below:

TABLE: AUTOCLAVE RESULTS Charge Product Sulfur, wt.%

Additionally, the autoclave catalyst indicated a carbon content of l0. l percent by weight.

We claim as our invention:

1; A process for converting an asphaltene-containing hydrocarbonaceous charge stock which comprises the steps of:

a. forming a reactive slurry of said charge stock, hydrogen and a finely divided catalyst of at least one metal component from the metals of Groups V-B, VI-B or VIII;

b. reacting said slurry, in a first reaction zone, at a temperature above about 300 C. and a pressure greater than about 500 p.s.i.g.;

c. separating the reaction zone effluent, in a first separation zone, at substantially the same pressure and a temperature above about 350 C. to provide a first vaporous phase and a catalyst-containing first liquid phase;

d. reacting said first liquid phase, in a second reaction zone,

at a pressure greater than about 500 p.s.i.g. and a temperature above about 300 C.; and,

e. recycling at least a portion of the resulting second zone effluent to combine with said charge stock.

2. The process of claim 1 further characterized in that said catalyst is an unsupported sulfide of at least one metal from Groups VB, VI-B and VIII.

3. The process of claim 1 further characterized in that said catalyst constitutes from 1.0 percent to about 25.0 percent by weight of said charge stock, as the elemental metal.

4. The process of claim 2 further characterized in that said catalyst is an unsupported vanadium sulfide.

5. The process of claim 1 further characterized in that said first vaporous phase is separated, in a second separation zone, at substantially the same pressure and a temperature from 60 F. to about 140 F. to provide a hydrogen-rich second vaporous phase and a second, normally liquid phase.

6. The process of claim 5 further characterized in that said second vaporous phase is recycled in part to said first and second reaction zones.

* l i i 

2. The process of claim 1 further characterized in that said catalyst is an unsupported sulfide of at least one metal from Groups V-B, VI-B and VIII.
 3. The process of claim 1 further characterized in that said catalyst constitutes from 1.0 percent to about 25.0 percent by weight of said charge stock, as the elemental metal.
 4. The process of claim 2 further characterized in that said catalyst is an unsupported vanadium sulfide.
 5. The process of claim 1 further characterized in that said first vaporous phase is separated, in a second separation zone, at substantially the same pressure and a temperature from 60* F. to about 140* F. to provide a hydrogen-rich second vaporous phase and a second, normally liquid phase.
 6. The process of claim 5 further characterized in that said second vaporous phase is recycled in part to said first and second reaction zones. 